code: def __str__(self):
      return f"NetworkDefinition(num_layers={len(self.__layers_by_id)})"
  
file_path: OMLT/src/omlt/neuralnet/network_definition.py
imports: import networkx
  from omlt.neuralnet.layer import Layer
label_desc: Use image node_id 15 for calling the NetworkDefinition obj's underlying member method code with example usage: obj.__str__() and returns: str, len, str